The purpose of these experiments is directed toward an understanding of suprathreshold auditory behavior among normal listeners and persons with sensorineural hearing loss. Several investigative areas have been undertaken to achieve this overall goal. Current experiments show that median loudness discomfort levels (LDL) and most comfortable loudness levels (MCL) for tonal and speech stimuli are relatively constant for hearing loss less than or equal to 50 dB HL, but became progressively higher with increasing hearing level. The difference between mean LDL and mean acoustic reflex thresholds (ART) for a variety of representative speech stimuli, as well as broad band and speech-spectrum noise stimuli, is relatively constant, although large individual variability precludes accurate prediction of the LDL from the ART. The current masking studies involve the detection of a tone in the presence of band-reject (notch) and low-pass noise signals. As the width of a "notch" centered on the tone is increased, detectability in normal ears initially is unaffected, then decreases, and finally approaches errorless performance. The decrease in performance suggest that the auditory filter concept does not account for detectability of tonal signals in "notch" noise. The functions relating the detectability of tonal signals in "notch" noise. The functions relating the detectability of a tonal signal and the cutoff frequency of a low pass masking noise differed substantially among three presbycusis subjects. All of the functions, however, were clearly different from normal hearing data.